<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style>#one{font-size:10px;}
#two{front-size:20px;}
#three{front-size:30px;}</style>
</head>
<body>
<p id="one">ID1</p>
<p id="two">ID2</p>
<p id="three">ID3</p>
</body>
</html>